NAME
POE::Quickie - A lazy way to wrap blocking code and programs
SYNOPSIS
use POE::Quickie;
sub event_handler {
# the really lazy interface, which will block
my ($stdout, $stderr, $exit_status) = quickie('foo.pl');
print $stdout;
# the more involved interface
quickie_run(
Program => ['foo.pl', 'bar'],
StdoutEvent => 'stdout',
Context => 'remember this',
);
# a combination of the two approaches
quickie_run(
Program => ['foo.pl', 'bar'],
Context => 'remember this',
ResultEvent => 'result',
);
}
# this will get called once for every output line
sub stdout {
my ($output, $context) = @_[ARG0, ARG1];
print "got output: '$output' in the context of '$context'\n";
}
# only called when the task is finished
sub result {
my ($pid, $stdout, $stderr, $merged, $status, $context) = @_[ARG0..$#_];
print "got all this output in the context of '$context':\n";
print "$_\n" for @$stdout;
}
DESCRIPTION
If you need nonblocking access to an external program, or want to
execute some blocking code in a separate process, but you don't want to
write a wrapper module or some POE::Wheel::Run boilerplate code, then
POE::Quickie can help. You just specify what you're interested in
(stdout, stderr, and/or exit code), and POE::Quickie will handle the
rest in a sensible way.
It has some convenience features, such as killing processes after a
timeout, and storing process-specific context information which will be
delivered with every event.
There is also an even lazier API which suspends the execution of your
event handler and gives control back to POE while your task is running,
the same way LWP::UserAgent::POE does. This is provided by the
"quickie_*" functions which are exported by default.
METHODS
"new"
Constructs a POE::Quickie object. You only need to do this if you want
to specify any of the parameters below, since a POE::Quickie object will
be constructed automatically when it is needed. The rest of the methods
can be called on the object ("$object->run()") or as class methods
("POE::Quickie->run()"). You can safely let the object go out of scope;
POE::Quickie will continue to run your processes until they finish.
Takes 3 optional parameters: 'debug', 'default', and 'trace'. These will
be passed to the object's POE::Session constructor. See its
documentation for details.
"run"
This method spawns a new child process. It returns its process id.
You can either call it with a single argument (string, arrayref, or
coderef), which will used as the 'Program' argument, or you can supply
the following key-value pairs:
'Program' (required), will be passed to directly to POE::Wheel::Run's
constructor.
'ProgramArgs' (optional), will be passed directly to POE::Wheel::Run's
constructor.
'Input' (optional), a string containing the input to the process. This
string, if provided, will be sent immediately to the child, and its
stdin will then be shut down. Note: no processing will be done on the
data before it is sent. For instance, if you are executing a program
which expects line-based input, be sure to end your input with a
newline.
'StdoutEvent' (optional), the event for delivering lines from the
process' STDOUT. If you don't supply this, they will be printed to the
main process's STDOUT. To explicitly ignore them, set this to "undef".
'StderrEvent' (optional), the event for delivering lines from the
process' STDERR. If you don't supply this, they will be printed to the
main process' STDERR. To explicitly ignore them, set this to "undef".
'ExitEvent' (optional), the event to be called when the process has
exited. If you don't supply this, a warning indicating the exit code
will be printed if it is nonzero. To explicitly ignore it, set this to
"undef".
'ResultEvent' (optional), like 'ExitEvent', but it will also contain all
the stdout/stderr generated by the child process.
'Context' (optional), a variable which will be sent back to you with
every event. If you pass a reference, that same reference will be
delivered back to you later (not a copy), so you can update it as you
see fit.
'Timeout' (optional), a timeout in seconds after which the process will
be forcibly killed if it is still running. There is no timeout by
default.
'AltFork' (optional), if true, a new instance of the active Perl
interpreter ($^X) will be launched with 'Program' (which must be a
string) as the code argument (*-e*), and the current @INC passed as
include arguments (*-I*). Default is false.
All other arguments will be passed to POE::Wheel::Run's "new" method.
Useful if you want to specify the input/output filters and such.
"killall"
This kills all processes which POE::Quickie is managing for your
session. Takes one optional argument, a signal name (e.g. 'SIGTERM').
"processes"
Returns a hash reference of all the currently running processes. The key
is the process id, and the value is the context variable, if any.
OUTPUT
The following events might get sent to your session. The names
correspond to the options to "run".
StdoutEvent
"ARG0": the chunk of STDOUT generated by the process
"ARG1": the process id of the child process
"ARG2": the context variable, if any
StderrEvent
"ARG0": the chunk of STDERR generated by the process
"ARG1": the process id of the child process
"ARG2": the context variable, if any
ExitEvent
"ARG0": the exit code ($?) of the child process
"ARG1": the process id of the child process
"ARG2": the context variable, if any
ResultEvent
"ARG0": the process id of the child process
"ARG1": an array of every chunk of stdout generated by the child process
"ARG2": an array of every chunk of stderr generated by the child process
"ARG3": an array of the interleaved stdout and stderr chunks
"ARG4": the exit code ($?) of the child process
"ARG5": the context variable, if any
FUNCTIONS
"quickie_run"
Equivalent to "POE::Quickie->run()", provided as a convenience.
Blocking functions
The following functions are modeled after the ones provided by
Capture::Tiny. They will not return until the executed process has
exited. However, "run_one_timeslice" in POE::Kernel will be called in
the meantime, so the rest of your application will continue to run.
They all take the same arguments as the "run" method, except for the
'*Event' and 'Context' arguments.
Note: Since these functions block, you must be careful not to call them
in event handlers which were executed with "$poe_kernel->call()" by
other sessions, so you don't hold them up. A simple way to avoid that is
to "yield()" or "post()" a new event to your session and do it from
there.
"quickie"
Returns 3 values: the stdout, stderr, and exit code ($?) of the child
process.
"quickie_tee"
Returns 3 values: an array of all stdout chunks, an array of all stderr
chunks, and the exit code ($?) of the child process. In addition, it
will echo the stdout/stderr to your process' stdout/stderr.
"quickie_merged"
Returns 2 values: an array of interleaved stdout and stderr chunks, and
the exit code ($?) of the child process. Beware that stdout and stderr
in the merged result are not guaranteed to be properly ordered due to
buffering.
"quickie_tee_merged"
Returns 2 values: an array of interleaved stdout and stderr chunks, and
the exit code ($?) of the child process. In addition, it will echo the
merged stdout & stderr to your process' stdout. Beware that stdout and
stderr in the merged result are not guaranteed to be properly ordered
due to buffering.
AUTHOR
Hinrik Örn Sigurðsson, hinrik.sig@gmail.com
LICENSE AND COPYRIGHT
Copyright 2010 Hinrik Örn Sigurðsson
This program is free software, you can redistribute it and/or modify it
under the same terms as Perl itself.
POD ERRORS
Hey! The above document had some coding errors, which are explained
below:
Around line 607:
You forgot a '=back' before '=head2'
Around line 625:
=back without =over